During fetus life there are vessel communications which normally disappear upon reaching adult life. These communications are called "ductus", among which arterial ductus, between the pulmonary artery and the aorta; venous ductus communicating the left umbilical vein to the heart right venous sinus; Cuvier ductus comprised of pairs of common cardinal veins; etc, may be mentioned.
When an individual reaches adult life and such ductus or fetal conduits persist, their closure is required by means of a surgery requiring thorax aperture.
Alternatively, during the last years intra-vascular treatments have been widely known in the medicine field. These are characterized by being carried out through the interior of the vessel lumen, instead of using surgery, i.e. instead of cutting tissues to reach the damaged artery or vein.
These intra-vascular treatments are effected within the vessel lumen, using different means and serving several purposes among which, the following may be mentioned: producing dilation of the artery or vein, dissolving thrombi therein, coating vessel inner walls with a prosthesis, recover the normal lumen of an artery dilated due to aneurysm and closing abnormal communications of these vessels, among others.
In case of abnormal vascular communications, the means used comprise occluding devices having shapes similar to plugs, umbrellas, springs, etc.
Some of the known devices used at present have the disadvantage that their size varies according to the ductus in which it will be used. Therefore, when the ductus is large, the artery access section constitutes a limitation.
Other devices used are Ivalon plugs and Rashkin umbrella. Particularly, in the latter, efforts have been made to solve its disadvantages by means of a device comprising a polyurethane double-umbrella. This is a device having at its ends corresponding sets of radially projected arms, similar to the rods of two umbrellas located one at each side of the ductus passage.
Such device, which is introduced by means of a catheter and pushing means and with the arms of both umbrellas folded in order to reach the operation region, is difficult to locate and unfold precisely. As a result, a complete occlusion is not attained in at least 15% of patients.
Further, the risk is run that, if one of the umbrellas slips off, it causes embolia at the lung. Further disadvantages is that such device is suitable for ductus up to 8 mm and it is expensive.
Other occluding devices are known comprised by a cylindrical spiral, having loops of equal diameter and a determined length. There are two types: Gianturco and Jackson. The latter has connecting means allowing its control and further it has fibers which, similar to small hairs, facilitate the formation of the occluding clot around the device. The device should be stretched at the intermediate region, due to which it adapts to the ductus passage, while the ends retaining their cylindrical spiral shape accommodate to the ends of the passage.
This kind of device is cheap and has reduced section, but limitation in use is of 3 mm; therefore it could not be employed for larger ductus which, on the other hand, are the majority.